Science : Dozing echidnas sleep like newborn babies

ROAMING about Australia are primitive mammals whose sleep patterns resemble those of newborn humans. Researchers in California and Australia believe this form of sleep represents a neurological "fossil".

Echidnas belong to a group called the monotremes, or egg-laying mammals. They do not show clear phases of deep sleep and rapid-eye-movement (REM) sleep like other mammals. Instead, they have just one, presumably primitive, form of sleep that looks like a combination of the two.

This finding, published in the 15 May issue of The Journal of Neuroscience (vol 16, p 3500), comes from a study by Jerry Siegel of the University of California, Los Angeles, and his colleagues at the University of Queensland in Brisbane. They worked on short-beaked echidnas, Tachyglossus aculeatus, among the most primitive mammals known, to learn more about the origins of mammalian sleep.

The researchers used electroencephalographs (EEGs) to measure brainwaves in the cortices of ...

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